Study On Pollution And Remediation Of Circumjacent Environment Of Municipal Wastewater Treatment Plant

As an important fundamental construction, the municipal wastewater treatment plants played an important role in remeding the wastewater and sewage. However, just because of its complicated particularity, most of municipal wastewater treatment plants have already been as a new pollution source while improving and beautifing the urban environment. Such pollution can be seen as following three aspects: emission of odorous compounds, inproper disposition of sludge and discharge of wastewater which can not reach the standard. Therefor, it is of great practical significance to conduct a study on pollution and remediation of circumjacent environment of mucinipal wastewater treatment plant.To the problem that quality of wastewater discharge can' t reach standard, some new reconstructive methods were carried out in addition to traditional actived sludge technology. In order to construct a complex biological treatment technique, sme suspended accessorial carrier were added in biological tank. With the same means, a polit-scale experiment (the influent is 3m³/d) was carried out successfully. In this test, kind of carriers, means of reoxygen and the ratio between quantity of carrier and COD of discharge, and so forth, all were taken into account. Accurate data about the compleat biological technology were achieved through this test and the result had been applied in actual process. The results of polit-scale test indicate that adding the plastic carrier to biological tank can increase the quantity of organism and enlarge the effective capacity of limited tank, and this method can improve the capability and efficiency of wastewater treatment. The results also indicate plastic carrier were more effective than trational fixed soft fibre in decreasing the concentration of COD in discharge, and mircobore installed at the bottom of tank were more efficient than surfical wheels in reoxygen. The optimal adding ratio of biological carrier was 15%, and 30% capability would be increased. The results of actual process indicate that such method can deal with excessive influent as usual, even there was 53% of influent exceeded the rated capacity, including COD,BOD₅,SS and other organic compounds. The operational expense of reconstructive complex biological treatment technology is less 1.03 million than traditional activated sludge process each year at least, and the one-off investment on construction would be decreased about 9.50 million, even without any additional ground was occupied. Thus it can be conducted that it was a good approach to apply the complex biological technique instead of trational activated sludge process for the same wastewater treatment plant.In this paper, some organic odorous sulfur containg compounds were studied through sampling and analyzing on site. At the same time, the distribution of some polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) also were studied carefully. By simulation in laboratory and in polit-scale experiment, the isotherm characters for quantity of adding biological carrier and quality of released wastewater were investigated. Surrounding the wastewater treatment plant, all of above three environmental problems were studied and discussed respectively in this paper. Due to the serious malodor pollution of wastewater treatment plant at present, some odorous organic sulfur containg compounds (MT, DMS, COS, CS₂, DMDS) distributed in water body and atmosphere were carefully identified and quantified by means of different analyzing methods at different treatment units. Further more, not only the distributing character of each compound was obtained, but also the mechanism of production and origin of these compounds were explained in detail. The results showed different units having the different concentrations for each compound, in spite of dissolving in water body or emiting to the atmosphere. Fortunately, after being treated by the full process, the odorous compounds distributed in water bodies and in atmosphere were decreased greatly, the removal rate was above 90%.The final treatment of sludge produced in wastewater treatment process is a very arduous work. Especially there are some persistent organic compounds, which were difficult to be degraded. In this paper, GC and GC-MS were used to analyse some man-made muskiness absorbed or dissolved in sludge, such as HHCB,AHTN,DPMI,ADBI,AHMI and DPMI. Results indicate that there were much quantity of man-made muskiness enriched in sludge, especially the Galaxolide and Tonalide. Further more, the distribution of some polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) also were studied carefully in this paper.